Java: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

Question

I have a class that will download a file from a https server. When I run it, it returns a lot of errors. It seems that I have a problem with my certificate. Is it possible to ignore the client-server authentication? If so, how?

package com.da;

import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.CharBuffer;
import java.util.concurrent.Future;

import org.apache.http.HttpResponse;
import org.apache.http.client.utils.URIUtils;
import org.apache.http.impl.nio.client.DefaultHttpAsyncClient;
import org.apache.http.nio.IOControl;
import org.apache.http.nio.client.HttpAsyncClient;
import org.apache.http.nio.client.methods.AsyncCharConsumer;
import org.apache.http.nio.client.methods.HttpAsyncGet;
import org.apache.http.nio.client.methods.HttpAsyncPost;

public class RSDDownloadFile {
    static FileOutputStream fos;

    public void DownloadFile(String URI, String Request) throws Exception
    {
        java.net.URI uri = URIUtils.createURI("https", "176.66.3.69:6443", -1, "download.aspx",
                "Lang=EN&AuthToken=package", null);
        System.out.println("URI Query: " + uri.toString());

        HttpAsyncClient httpclient = new DefaultHttpAsyncClient();
        httpclient.start();
        try {
            Future<Boolean> future = httpclient.execute(
                    new HttpAsyncGet(uri),
                    new ResponseCallback(), null);

            Boolean result = future.get();
            if (result != null && result.booleanValue()) {
                System.out.println("\nRequest successfully executed");
            } else {
                System.out.println("Request failed");
            }              
        } 
        catch(Exception e){
            System.out.println("[DownloadFile] Exception: " + e.getMessage());
        }
        finally {
            System.out.println("Shutting down");
            httpclient.shutdown();
        }
        System.out.println("Done");  

    }

    static class ResponseCallback extends AsyncCharConsumer<Boolean> {

        @Override
        protected void onResponseReceived(final HttpResponse response) {
             System.out.println("Response: " + response.getStatusLine());
             System.out.println("Header: " + response.toString());
             try {   
                 //if(response.getStatusLine().getStatusCode()==200)
                     fos = new FileOutputStream( "Response.html" );
             }catch(Exception e){
                 System.out.println("[onResponseReceived] Exception: " + e.getMessage());
             }
        }

        @Override
        protected void onCharReceived(final CharBuffer buf, final IOControl ioctrl) throws IOException {
            try
            {
                while (buf.hasRemaining()) 
                {
                    //System.out.print(buf.get());
                    fos.write(buf.get());
                }
            }catch(Exception e)
            {
                System.out.println("[onCharReceived] Exception: " + e.getMessage());
            }
        }

        @Override
        protected void onCleanup() {
            try
            {             
                if(fos!=null)
                    fos.close();
            }catch(Exception e){
                System.out.println("[onCleanup] Exception: " + e.getMessage());         
            }
             System.out.println("onCleanup()");
        }

        @Override
        protected Boolean buildResult() {
            return Boolean.TRUE;
        }

    }
}

Errors:

URI Query: https://176.66.3.69:6443/download.aspx?Lang=EN&AuthToken=package
Aug 2, 2011 3:47:57 PM org.apache.http.impl.nio.client.NHttpClientProtocolHandler exception
SEVERE: I/O error: General SSLEngine problem
javax.net.ssl.SSLHandshakeException: General SSLEngine problem
    at com.sun.net.ssl.internal.ssl.Handshaker.checkThrown(Unknown Source)
    at com.sun.net.ssl.internal.ssl.SSLEngineImpl.checkTaskThrown(Unknown Source)
    at com.sun.net.ssl.internal.ssl.SSLEngineImpl.writeAppRecord(Unknown Source)
    at com.sun.net.ssl.internal.ssl.SSLEngineImpl.wrap(Unknown Source)
    at javax.net.ssl.SSLEngine.wrap(Unknown Source)
    at org.apache.http.impl.nio.reactor.SSLIOSession.doHandshake(SSLIOSession.java:154)
    at org.apache.http.impl.nio.reactor.SSLIOSession.isAppInputReady(SSLIOSession.java:276)
    at org.apache.http.impl.nio.client.InternalClientEventDispatch.inputReady(InternalClientEventDispatch.java:79)
    at org.apache.http.impl.nio.reactor.BaseIOReactor.readable(BaseIOReactor.java:161)
    at org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvent(AbstractIOReactor.java:335)
    at org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvents(AbstractIOReactor.java:315)
    at org.apache.http.impl.nio.reactor.AbstractIOReactor.execute(AbstractIOReactor.java:275)
    at org.apache.http.impl.nio.reactor.BaseIOReactor.execute(BaseIOReactor.java:104)
    at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor$Worker.run(AbstractMultiworkerIOReactor.java:542)
    at java.lang.Thread.run(Unknown Source)
Caused by: javax.net.ssl.SSLHandshakeException: General SSLEngine problem
    at com.sun.net.ssl.internal.ssl.Alerts.getSSLException(Unknown Source)
    at com.sun.net.ssl.internal.ssl.SSLEngineImpl.fatal(Unknown Source)
    at com.sun.net.ssl.internal.ssl.Handshaker.fatalSE(Unknown Source)
    at com.sun.net.ssl.internal.ssl.Handshaker.fatalSE(Unknown Source)
    at com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(Unknown Source)
    at com.sun.net.ssl.internal.ssl.ClientHandshaker.processMessage(Unknown Source)
    at com.sun.net.ssl.internal.ssl.Handshaker.processLoop(Unknown Source)
    at com.sun.net.ssl.internal.ssl.Handshaker$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.net.ssl.internal.ssl.Handshaker$DelegatedTask.run(Unknown Source)
    at org.apache.http.impl.nio.reactor.SSLIOSession.doHandshake(SSLIOSession.java:180)
    ... 9 more
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.validator.PKIXValidator.doBuild(Unknown Source)
    at sun.security.validator.PKIXValidator.engineValidate(Unknown Source)
    at sun.security.validator.Validator.validate(Unknown Source)
    at com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.checkServerTrusted(Unknown Source)
    at com.sun.net.ssl.internal.ssl.JsseX509TrustManager.checkServerTrusted(Unknown Source)
    ... 16 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(Unknown Source)
    at java.security.cert.CertPathBuilder.build(Unknown Source)
    ... 21 more
onCleanup()

[DownloadFile] Exception: javax.net.ssl.SSLHandshakeException: General SSLEngine problem
Shutting down
Done

Answer 1

The problem appears when your server has self signed certificate. To workaround it you can add this certificate to the list of trusted certificates of your JVM.

In this article author describes how to fetch the certificate from your browser and add it to cacerts file of your JVM. You can either edit JAVA_HOME/jre/lib/security/cacerts file or run you application with -Djavax.net.ssl.trustStore parameter. Verify which JDK/JRE you are using too as this is often a source of confusion.

See also: How are SSL certificate server names resolved/Can I add alternative names using keytool? If you run into java.security.cert.CertificateException: No name matching localhost found exception.